Acidic electrochemical CO 2 reduction (CO 2 RR) to high-value C 2+ products offers a promising route for CO 2 utilization. However, it still faces severe challenges: competitive hydrogen evolution reaction (HER) and slow C C coupling. To address these issues, we propose a defect engineering strategy by Fe-doped carbon nitride (FeCN) modification to reduce Cu defect formation energy, thereby inducing abundant and stable surface defects. We synthesized a magnetron-sputtered Cu nanoparticle (MSCu) catalyst modified with FeCN (MSCu-FeCN) and evaluated its performance in a membrane electrode assembly (MEA) under acidic conditions. At 500 mA·cm −2 , MSCu-FeCN achieves a remarkable C 2+ Faradaic efficiency (FE) of 73.07 % and a single-pass CO 2 conversion efficiency (SPCE) of 57.30 % with a full-cell voltage of 3.88 V, significantly superior to the original MSCu. Density functional theory (DFT) calculations, cyclic voltammetry curves, and in-situ attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy confirm that FeCN lowers Cu defect formation energy, increases surface defect density, enhances *CO intermediate coverage, thereby promoting C C coupling. This work presents a defect engineering approach enabling high-efficiency acidic CO 2 RR, while providing pivotal insights for industrial-grade electrocatalytic systems.
Conventional high-temperature synthesis for peroxymonosulfate (PMS) catalysts is typically confined to the range of 200–900 °C, leaving the properties and mechanisms of catalysts synthesized at ultra-high temperatures (>1000 °C) as an open question. This study systematically investigated preparation temperatures ranging from 800 to 1600 °C by developing a series of Fe-C-N-based catalysts, using the pharmaceutical pollutant esmolol (ES) as a model contaminant to evaluate PMS activation performance. The 1400-FeCN catalyst synthesized at 1400 °C demonstrated optimal performance, achieving 95 % ES degradation within 15 min (pseudo-first-order rate constant: 0.21 min −1 ) while maintaining stable activity across a broad pH range (7.4–9.4). The system exhibited remarkable tolerance to common aqueous anions (Cl − , SO 4 2− , CO 3 2− , ClO 4 − ) and maintained effective degradation performance in real hospital wastewater matrices. Mechanistic studies identified iron(IV)-oxo (Fe IV =O) complexes as the dominant reactive species responsible for contaminant oxidation. This work establishes both fundamental principles and practical methodologies for developing ultra-high-temperature PMS catalysts.
Knowledge about the impact of singlet oxygen ( 1 O 2 ) on the characteristics and inactivation of harmful cyanobacterial organic matter is limited. In this study, the feasibility of using an improved single-iron doped graphite-like phase carbon nitride catalyst (FeCN) to activate peroxymonosulfate (PMS) catalytic production of 1 O 2 to inactivate four harmful cyanobacteria was investigated. The inactivation efficiencies at 30 min were 92.77%, 66.84%, 91.06%, and 93.45% for Microcystis aeruginosa ( M. aeruginosa ), Nodularia harveyana , Oscillatoria sp., and Nostoc sp . , respectively. This was associated with adjusting experimental parameters, such as the FeCN and PMS doses and initial pH, to obtain the maximum 1 O 2 yield. The quenching experiment results and electron paramagnetic resonance spectra showed that 1 O 2 generated via the non-radical pathway might play a dominant role in inactivating harmful cyanobacteria and degrading harmful algal toxins (Microcystin-LR and Nodularin). In addition, the FeCN-PMS system not only effectively destroyed the integrity of harmful cyanobacterial cells but also effectively degraded cyanobacterial toxins , thereby preventing severe secondary contamination by cell rupture. A possible removal mechanism was proposed. This reveals the potential of 1 O 2 to simultaneously inactivate harmful cyanobacteria and degrade harmful cyanobacterial toxins.
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